System and method for producing devices including a semiconductor part and a non-semiconductor part

ABSTRACT

A system produces devices that include a semiconductor part and a non-semiconductor part. A front end is configured to receive a semiconductor part and to process the semiconductor part. A back end is configured to receive the processed semiconductor part and to assemble the processed semiconductor part and a non-semiconductor part into a device. A transfer device is configured to automatically handle the semiconductor part in the front end and to automatically transfer the processed semiconductor part to the back end.

TECHNICAL FIELD

Embodiments of the invention relate to a system and to a method forproducing devices including a semiconductor part and a non-semiconductorpart.

BACKGROUND

Conventional processes for manufacturing a device including asemiconductor part and a non-semiconductor part comprise, for example,processes for producing power disc devices. Such power disc devices,also known as STD pellets, are formed of a stack of a plurality of discscomprising a silicon disc sandwiched between pairs of copper andmolybdenum discs. The silicon disc has its outer edges beveled, and theplanar main surfaces thereof may be covered with an Al metallization.Conventional processes for generating such a device comprise a manualworkplace for etching the silicon disc at its periphery, a manualworkplace for assembly of the discs of silicon, copper and molybdenuminto a stack, and a manual workplace for providing a passivation of theexposed edge of the silicon disc extending beyond the copper andmolybdenum discs. Further, manual processes for inspection are providedand the respective elements are handled manually between the respectiveworkplaces.

SUMMARY OF THE INVENTION

Embodiments of the invention provide a system for producing devicesincluding a semiconductor part and a non-semiconductor part, the systemcomprising:

a front end configured to receive a semiconductor part and to processthe semiconductor part;

a back end configured to receive the processed semiconductor part and toassemble the processed semiconductor part and a non-semiconductor partinto a device; and

a transfer device configured to automatically handle the semiconductorpart in the front end and to automatically transfer the processedsemiconductor part to the back end.

Embodiments of the invention provide a system for producing a power discdevice comprising a semiconductor disc sandwiched between a plurality ofmetal discs, the system comprising:

a front end semiconductor processing station comprising a plurality ofetching stations and a test station, the etching station beingconfigured to etch an edge of a semiconductor disc, and the test stationbeing configured to test the etched semiconductor disc;

a back end device assembly station comprising:

an assembly station configured to assemble the etched semiconductor discand a plurality of metal discs into a stack, wherein the semiconductordisc has a larger diameter than the metal discs,

a passivation station configured to apply a passivation material to theedge of the stack to cover the exposed area of the semiconductor disc,and

a heating station configured to receive the passivated stack and to heatthe stack; and

a robot comprising an arm provided with a gripper and configured tohandle the semiconductor disc in the front end semiconductor processingstation and to transfer the etched semiconductor disc from the front endsemiconductor processing station to the back end device assemblystation.

Embodiments of the invention provide a system for producing devicesincluding a semiconductor part and a non-semiconductor part, the systemcomprising:

a front end receiving a semiconductor part and processing thesemiconductor part;

a back end receiving the processed semiconductor part and thenon-semiconductor part and assembling the parts into a device; and

means for automatically handling the semiconductor part in the front endand for automatically transferring the processed semiconductor part tothe back end.

Embodiments of the invention provide a method for producing devicesincluding a semiconductor part and a non-semiconductor part, the methodcomprising:

receiving and processing at a front end processing station asemiconductor part;

receiving and assembling at a back end processing station the processedsemiconductor part and a non-semiconductor part; and

automatically handling the semiconductor part in the front endprocessing station and automatically transferring the processedsemiconductor part to the back end processing station by a transferdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a power device, wherein FIG. 1A is anisometric, exploded view of the different discs used, and FIG. 1B is across-sectional representation of the device;

FIG. 2 shows an overview of the system including the linked front endand back end equipment;

FIG. 3 is an enlarged view of the back end cluster described with regardto FIG. 2;

FIG. 4 shows an example of the robots used in the back end cluster,wherein FIG. 4A shows a first robot, and wherein FIG. 4B shows thegripper of a second robot;

FIG. 5 shows details of the assembly station depicted in FIG. 3, whereinFIG. 5A shows an isometric view of the assembly station, wherein FIG. 5Bshows an enlarged view of a reception area of the assembly station,wherein FIG. 5C shows a bracket of a centering device in a positioncentering a lower metal disc, and wherein FIG. 5D shows a bracket of acentering device in a position centering an upper metal disc;

FIG. 6 is a photographic representation of a stack of silicon, copper,and molybdenum discs;

FIG. 7 is an enlarged view of the passivation station shown in FIG. 3;

FIG. 8 is a photographic representation of a passivated stack;

FIG. 9 shows monitoring systems, wherein FIG. 9A schematically shows acamera positioned at the assembly block, and wherein FIG. 9Bschematically shows a camera positioned at the passivation station;

FIG. 10A shows the positions at which the pictures are taken by themonitoring systems of FIG. 9;

FIG. 10B shows the passivated stack and the dimensions measured by themonitoring system;

FIG. 11 shows the heating station, wherein FIG. 11A shows the heatingstation comprising the plurality of heating devices, wherein FIG. 11Bshows one heating device in its open state, and wherein FIG. 11C shows aheating device in its closed state; and

FIG. 12 shows a photographic representation of an open heating deviceafter preheating the stack.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The semiconductor industry is typically embedded in Frontend and Backend(FE and BE) production. Quality management between FE and BE is achallenge and mainly based on people's knowledge and behavior. Forreducing maintenance costs, stop lost production, eradicate unplannedoutages and equipment breakdowns, the handling steps need to beimproved, e.g., manual handling steps need to be eliminated, especiallymanual chip (wafer) transportation after chip test.

For example, known processes for producing power disc devices are manualprocesses including the beveling process of the semiconductor disc usedin the device either chemically by etching or mechanically. Also theassembly and the passivation processes are manual processes. Therefore,the current process for generating such devices is slow, inaccurate,inefficient and prone to producing rejects due to the manual workinvolved.

Thus, a need exists for an approach allowing the production of suchdevices with a high volume and a high quality.

Embodiments of the invention provide a highly automatedassembly/passivation process integrated into an advanced design of anetching cluster which allows for a reduction of process steps therebyrealizing stable processing to increase productivity. In accordance witha first aspect of the invention, a front end cluster and a back endcluster for the manufacturing process of the disc devices are integratedor linked. In accordance with a second aspect, an advanced assemblystation is provided. In accordance with a third aspect of the invention,an advanced passivation station is provided. In accordance with a fourthaspect of the invention, a dynamic process control system controllingthe assembly and passivation of the power disc devices is provided. Inaccordance with a fifth aspect, an advanced preheating station isprovided. Embodiments of the invention provide for a quality improvementby providing a fully automated etch and passivation technology and dueto an intermediate chip transportation using a robot system.

Embodiments of the invention will now be described with regard to asystem or process for producing disc-shaped power devices in the form ofa plurality of metal discs and a silicon disc assembled to a stack.

FIG. 1 shows an example of such a power device, wherein FIG. 1A is anisometric, exploded view of the different discs used, and FIG. 1B is aschematic cross-sectional representation of the device. The devicecomprises a silicon disc 100 sandwiched between metal discs. Morespecifically, on an upper surface 102 of the silicon disc, a molybdenumdisc 104 is provided on top of which a copper disc 106 is arranged. On alower surface 108 of the silicon disc 100 a further molybdenum disc 110is arranged below which a further copper disc 112 is provided. Therespective discs 100 to 112 are stacked on top of each other in a way asshown in FIG. 1A and are centered with respect to a central axis 114. Asis shown in FIG. 1B, the silicon disc 100 may be provided with analuminum metallization 100 a and 100 b. The silicon disc 100 has alarger diameter than the remaining discs so that an outer edge 116 ofthe silicon disc 100 extends radially further outward than an outer edge118 of the remaining discs 104, 106, 110 and 112. The part 120 of thesilicon disc 100 extending beyond the edge 118 is beveled so that thecross-sectional shape of portion 120 is tapered. The thickness of thedisc portion 120 is reduced from a thickness at a center 114 towards theouter edge 116 of the disc 100. The portion 120 is the exposed edgeregion of the silicon disc, i.e., the portion not covered by the otherdiscs. Inside the silicon disc two pn junctions are provided, one closeto the upper surface 102 and one close to the lower surface 108. Toprovide for a sufficiently long electrical path along the upper andlower surface and around the edge 116 the tapered structure of the edgeportion 120 is used.

For processing or manufacturing a device having a structure as shown inFIG. 1, a front end process cluster (e.g., a spin-etch cluster) isprovided. In the front end process cluster the silicon disc 100 isprocessed or treated for shaping the portion 120 of the disc in a wayshown in FIG. 1B. A back end cluster or assembly cluster is provided forjoining the disc 100 with the molybdenum and copper discs to form astack. Since the edge portion 120 of the silicon disc 100 has beenetched, i.e. thinned, it is very sensitive and should not be contactedduring the handling. In addition the edge portion 120 extends beyond theedge 118 of the other discs in the stack. Therefore, after assemblingthe respective discs to a stack a passivation 122 is applied so as tocover the exposed area 120 of the silicon chip 100. Following thepassivation, the stack is preheated and then forwarded to furtherprocessing. After the preheating step, the stack with the passivationhas a sufficient stability and can be easily handled.

Embodiments of the first aspect of the invention will now be described.In accordance with the first aspect of the invention the front end orspin-etch cluster and the back end cluster or assembly cluster arelinked.

FIG. 2 shows an overview of the system including the linked front endand back end equipment. As mentioned above, the front end equipment isused for handling and treating (processing) the semiconductor disc 100(see FIG. 1). The front end cluster 200 comprises three etch modules 202a to 202 c each including an etch chamber for receiving a single disc100. Inside the etch chamber, the disc is received and rotated. Duringrotation an etching liquid is sprayed onto the edge portion 120 of thedisc 100 for obtaining the tapered structure discussed above. The frontend further comprises a test station 204. The test station 204 receivesan etched or treated silicon disc and determines whether the silicondisc has predefined electrical characteristics and also whether thedesired degree of etching at the portion 120 was achieved. The front endcluster 200 further comprises a robot 206 comprising an arm 208 beingprovided with a gripper (not shown) and being rotatable around six axes.The robot arm 208 is provided for handling the silicon discs inside thefront end cluster 200, more specifically for inserting the non-treateddiscs into the respective etch stations 202 a to 202 c and into the teststation 204. The front end further comprises a control element 210 foroptically controlling a silicon disc held by the robot arm 208. Therobot arm 208 holding a disc moves into the control device 210 and by anoptical inspection it is determined whether the disc has a predefinedshape and structure or whether any defects are present so that the discmay be rejected. In addition, the position of the disc in the gripperwith respect to the robot arm 208 is determined, so that on the basis ofthis information the robot 206 can be controlled by the controller 212to insert the disc into the etch stations 202 a to 202 c and inside thetest station 204 at the correct position. For example, in case thesilicon disc is not exactly centered with regard to the gripper by meansof the control device 210 this “mispositioning” is detected so that therobot 206 is controlled to make an additional movement to ensure thatthe disc is correctly placed, for example, on the spinning table insidethe etch station.

The front end 200 further comprises a plurality of inputs 214 a to 214 ceach receiving an input tray provided in respective magazines 216 a to216 c. In addition, the front end 200 comprises reject outputs 218 a and218 b. The inputs and outputs 214 and 218 receive respective trays thatare adapted to hold a plurality of silicon discs. The robot 206 iscontrolled by means of the controller 212 to take from one of the inputtrays provided at the inputs 214 a to 214 c an untreated semiconductordisc, to check its structure and its position in the control device 210and to input it into one of the etch stations 202 a to 202 c. In case itis determined that the silicon disc 100 is defective, rather thaninputting it into one of the etch stations the robot 206 is controlledto place this defective silicon disc in one of the trays provided in thereject outputs 218 a and 218 b. Also, in case the test station 204yields a test result for a processed silicon disc 100 indicating that atest failed, i.e., that the silicon disc being etched was not valid, bymeans of the robot 206 this disc will be placed in the reject output 218a or 218 b. It may also be that the test station 204 indicates that theetching was not sufficient, and in such a situation, instead of placingthe silicon disc into one of the reject bins, it is again introducedinto an etch station which is controlled to provide for an additionaletching that was determined, for example, with regard to the duration,on the basis of the results from the test station. In case the silicondisc after this additional etch test passes the test, it can be furtherprocessed.

FIG. 2 further shows the back end cluster 300 used for assembling thepower disc devices. The back end cluster 300 comprises an intermediatetray 302 positioned at the interface between the front end cluster 200and the back end cluster 300. The back end cluster 300 comprises anassembly station and a passivation station that is commonly indicated inFIG. 2 by reference sign 304. The back end cluster 300 further comprisesa heating station 306 comprising a plurality of individual heatingentities. The back end cluster 300 further comprises a plurality ofinput magazines 308 for providing the metal discs, namely the copperdiscs and the molybdenum discs. The back end cluster 300 comprises tworobots 310 and 312, wherein the robot 310 is provided for taking fromthe intermediate tray 302 a processed or treated silicon disc receivedfrom the front end cluster 200 and to forward it to theassembly/passivation station 304. In a similar way as in the front endcluster 200, also in the back end cluster 300 a control device 314 isprovided for optically determining a position of the treated silicondevice held by the robot 310 for allowing a correct placement thereof inthe assembly station 304. The position of the disc held by the robot 310is determined with respect to the structure of the robot so that therobot can be controlled accordingly to place the disc at a desiredposition. The robot 310 is further provided for transferring apassivated stack from the passivation station 304 to the heating station306, again via a control device 318 for controlling the passivated stackand its position. The robot 310 also obtains the preheated devices orpellets from the heating device 306 and provides them in an output tray320 from which the processed devices can be forwarded to furtherprocessing stations. The robot 312 is provided for obtaining from theinput 308 the respective molybdenum and copper discs and for placingthem in the assembly station 304. A control device 316 is provided forinspecting the discs received from the input 308 to ensure that nodefects are present in the discs and that also to determine a positionthereof with respect to the robot 312.

In accordance with embodiments of the first aspect of the invention,FIG. 2 shows a system in which the front end cluster 200 and the backend cluster 300 are linked via the robot 206 provided in the front endcluster 200. The robot 206 transfers silicon devices from the teststation 204, in case they passed the test, to the intermediate tray 302,from which they can be transferred into the assembly station by means ofthe robot 310.

Thus, in accordance with the first aspect of the invention, thedrawbacks of conventional processes are avoided, as all processing stepsare automated, especially the transfer between the front end cluster 200and the back end cluster 300, thereby avoiding any manual handling andcontact with a device until it has a sufficiently stable structure afterthe heating in the heating station 306.

The integrated system linking the front end cluster 200 and the back endcluster 300 in the above described way overcomes the problems describedabove and associated with the manual processing, especially the manualtransfer between the front end and the back end. Linking the front endand back end clusters as described in accordance with embodiments of theinvention provides an advanced equipment integration technology to avoiddamages on a chip during transportation after wafer test. In accordancewith embodiments, one or more video cameras, one or more vision systemsand a plurality of integrated sensors are used for providing real timefeed back to a technician and maintenance for troubleshooting andpredictive maintenance.

In the embodiment described with regard to FIG. 2, a robot 206 wasprovided for allowing handling of the semiconductor discs in the frontend and for transferring the semiconductor discs after treatment to theback end cluster 300. It is noted that the inventive approach is notlimited to this implementation of the link between the front end clusterand the back end cluster, rather instead of the robot 206 any kind oftransfer device allowing handling the discs inside the front end andtransferring the discs from the front end to the back end is possible.

For example, the means for automatically handling the semiconductor partin the front end and for automatically transferring the processedsemiconductor part to the back end or the transfer device configured toautomatically handle the semiconductor part in the front end and toautomatically transfer the processed semiconductor part to the back endmay comprise a carrousel having one or more portions for receiving thesemiconductor part. The one or more portions pass the respectivestations in the front end (e.g., the one or more etch stations, the oneor more control stations and the one or more test stations as well asthe one or more input ports and reject ports). In addition, the frontend, the back end and the carrousel are arranged such that theintermediate tray is passed for transferring the processed semiconductorelement from the front end to the back end. The carrousel may beprovided with a charger/de-charger element for transferring thesemiconductor between the respective stations and the portion on thecarrousel. The carrousel may comprise one or more charger/dechargerelements for servicing the one or more portions. Alternatively,respective charger/decharger elements may be provided at the respectivestations in the front end and at the intermediate tray.

In accordance with other embodiments, a conveyor may be provided forimplementing the transfer device or the means for transferring. Forexample, a belt conveyor may be provided which extends such that ispasses the respective stations in the front end (see, e.g., above) andthe intermediate tray between the front end and the back end. Thesemiconductor elements may be provided on the conveyor directly or maybe arranged on/in a transport pod moving along the conveyor. Again,respective charger/decharger elements may be provided.

In yet another embodiment, the transfer device or the means fortransferring may be implemented using a self-propelled, automaticallycontrolled carriage that receives one or more semiconductor elements orone or more transport pods and that is controlled to move to therespective stations in the front end and to the intermediate tray.Again, respective charger/decharger elements may be provided.

In the following, further aspects of the invention will be describedwhich are a part of the back end cluster 300.

FIG. 3 is an enlarged view of the back end cluster 300 already describedwith regard to FIG. 2. FIG. 3 is a view from the interface between thefront end cluster 200 and the back end cluster 300. Theassembly/passivation station 304 comprises an assembly block 322comprising two assembly stations 322 a and 322 b. The assembly stations322 a and 322 b are provided on a rotatable table 324 so that thestation 322 a can be rotated from the position shown in FIG. 3 to theposition at which station 322 b in FIG. 3 is. Likewise, by rotating thetable 324 the station 322 b can be moved from the position shown in FIG.3 to the position of station 322 a. Further, the back end cluster 300comprises a passivation station 326 comprising a nozzle device 328comprising a top nozzle 328 a and a bottom nozzle 328 b for providingthe passivation material at the edge of the silicon disc on its upperand lower surfaces and on the outer edge.

In FIG. 3 the assembly station 322 a is at the position where therespective discs, the silicon disc and the copper and molybdenum discs,are put on top of each other. After the stacking is completing aclamping force is applied and the stack is raised. The table 324 is thenturned so that the assembly station is at the position of assemblystation 322 b and the stack is raised in such a way that the edge of thesilicon disc is between the upper and lower nozzles 328 a and 328 b. Theassembly stations 322 a and 322 b allow a rotation of the stack whilemaintaining the clamping pressure, thereby allowing the application ofthe passivation material by means of the nozzle 328 a to 328 b aroundthe entire periphery.

The heating station 306 comprises a plurality of individual heatingdevices 336 a to 336 j, which can be selectively activated dependent onthe throughput of devices in the system.

The output 320 of the back end cluster 300 comprises an output traymagazine 330 receiving a plurality of trays holding already completeddevices. A transport system 332 is provided for placing an output tray334 at a station where, by means of the robot 310 completed devices canbe transferred from the heating station 306 to the tray 334. Once thetray 334 is filled it is moved into the magazine 320 and a new, emptytray is provided.

FIG. 4 shows an example of the robots 310, 312 used in the back endcluster 300 in accordance with embodiments of the invention. FIG. 4Ashows the robot 312 comprising a stand 338 to which an arm 340 isrotatably mounted. The arm 340 can be rotated about two parallel axis,namely axis 342 and 344 and at a forward end of the arm a gripper 346 isattached. The robot 312 comprises a gripper 346 having two suctionelements 348 a and 348 b that are used for gripping and placing thecopper and molybdenum discs from the input 308 into the assembly station322 a. Dependent on the size of the discs to be handled, either gripperelement 348 a or gripper element 348 b is used. The structure of therobot 310 is basically the same as that of robot 312 except that thegripper is different. FIG. 4B shows the gripper 350 of the robot 310comprising a first gripper element 352 a and a second gripper element352 b. The gripper element 352 a is a suction element that is used fortaking a processed silicon disc from the intermediate tray 302 and forplacing it via the control device 314 into the assembly station 322 a.Once the passivation process is completed, the passivated stack which isstill clamped by the assembly station returns to position 322 a. Forremoving the passivated stack from the assembly station the gripper 352b is used. Other than gripper 352 a having the suction head depicted inFIG. 4B, the gripper element 352 b comprises two lower bars 354 a and354 b and one upper bar 356. The upper and lower bars are moveable withrespect to each other. In the embodiment of FIG. 4B the upper bar 356 ismoveable in a vertical direction, thereby allowing to apply a clampingforce to an element held between the bars 354 a, 354 b and 356. Theclamping structure of the assembly stations 322 a and 322 b isconfigured in such a way that the upper bar 356 of gripper 352 b passesthrough a hole in an upper stamp and the lower bars 354 a and 354 breceive a lower stamp there between. The bars are moved with respect toeach other to apply a clamping force to the passivated stack and onlyonce a clamping force starts to be applied to the passivated stack theclamping elements of the assembly station 322 a will be removed. Thus,when transferring the passivated stack using the robot 310 the grippermechanism 352 b ensures that a continuous clamp force is applied to thestack.

The individual heating devices 336 a to 336 j of the heating station 306are provided with two heating brackets that can be vertically moved withrespect to each other. These heating brackets are configured in such away that when placing a passivated stack by means of the gripper arm 352b into one of the heating devices the brackets are closed and apply apressure to the passivated stack. Only once the brackets are closed andbegin to start applying a pressure the bars 354 a, 354 b and 356 of thegripper 352 b release the clamping force and are finally removed fromthe heating station.

In the following, further details of embodiments of the second aspect ofthe invention will be described. In accordance with the second aspect ofthe invention an advanced assembly station is provided and embodimentsthereof will now be described with reference to FIG. 5.

FIG. 5A shows an isometric view of an example of the assembly station322 a also shown in FIG. 3. The assembly station 322 a comprises areception area 360 at which the respective discs to be assembled into astack are received. The assembly station 322 a comprises a centeringdevice 362 and a clamping device 364. The clamping device 364 comprisesa lower stamp 364 a and an upper stamp 364 b. The stamps 364 a and 364 bare moveable in a vertical direction and with respect to each other.More specifically, the lower stamp 364 a is moveable from a lowerposition in which its upper surface is substantially flush with asurface 360 a of the reception area to an extended position as shown inFIG. 5A. The upper stamp 364 b is also moveable in a vertical direction.More specifically, it is moveable from a retracted position downward tocontact an upper surface of the stack. The two stamps are movedvertically in such a way that a desired clamping force is applied to thestack. The two stamps 364 a and 364 b are controlled to be movedvertically upward for providing the stack that is shown in FIG. 5( a) atreference sign 366 at a position elevated above the reception area 360.This allows the two nozzles of the passivation station (see FIG. 3) toapply the passivation material from above and from below to the edge 368of the stack 366. The assembly station 322 a further comprises a drive370 comprising belts 370 a and 370 b for rotating the stamps 364 a and364 b, thereby allowing a rotation of the stacks 366 clamped therebetween. The upper stamp 364 b comprises an opening 372 so that thelower end of the upper stamp 364 b is fork-shaped. The opening 372 isprovided for receiving the upper bar 356 of the gripper 350 of the robot310. The lower stamp 364 a has a smaller diameter than the upper stamp364 b and its diameter is selected such that the lower stamp 364 a canbe received between the two lower bars 354 a and 354 b of the gripper350 of the robot 310.

FIG. 5B shows an enlarged view of the reception area 360 of the assemblystation 322 a. The centering device 362 comprises three brackets 374 ato 374 c which are arranged at equal distances or intervals around acentral part of the reception area 360 where the respective discs arereceived. The brackets 374 a-374 c are moveable in a radial directioninwardly and outwardly with respect to a center of the reception area360 and vertically upwards and downwards. For producing the stack, in afirst step depicted in FIG. 5C the lower copper disc 112 and the lowermolybdenum disc 110 are placed on the reception area 360. When placingthe discs onto the reception area 360 the brackets 374 a are in theirradially retracted position. Once the discs 110 and 112 are placed, thethree brackets are moved radially inward so that a forward part 376 ofthe brackets 374 a-374 c contacts the two discs. Due to the arrangementof the three brackets, the radial inward movement thereof results in acentering of the discs with regards to the center C of the desiredstack. Subsequently, the silicon disc 100 is placed onto the layers 110and 112. As mentioned above, the position of the disc 100 with regard tothe gripping device is determined by the control devices provided in theback end cluster 300 so that the robot 210 can be controlled on thebasis of this position information in such a way that the disc 100 isalso centered. An active centering of the disc using the brackets is notpossible as any contact with the etched peripheral portion of thesilicon disc would damage the disc which needs to be avoided. Followingthe placement of the silicon disc the upper molybdenum layer 104 and theupper copper layer 106 are placed on top of the disc 100. The brackets374 are radially retracted by a distance so that the part 376 of thebrackets 374 can pass the outer edge of the silicon disc 100 when thebrackets are moved vertically upward. Once the part 376 clears the disc100 a radially inward movement of the brackets occurs thereby centeringthe discs 104 and 106 in the same way as the lower discs 112 and 110. Inthe embodiment shown in FIG. 5, the brackets 374 are provided with aslit 378 receiving the outer edge of the silicon disc 100 when thebracket is at the position shown in FIG. 5D. However, other embodimentsmay provide for a bracket comprising only the extension 376 extendingfrom the main body of the bracket 374 without the material below theslit 378.

Once all of the discs are centered, the brackets 374 are refracted, andthe stamps 364 a and 364 b are activated for clamping the stack 366 andholding it at a position shown in FIG. 5A.

FIG. 6 is a photographic representation showing the stack 366 comprisingthe disc 100, the copper disc 106, the molybdenum disc 104 as well asthe lower molybdenum disc 110 and lower copper disc 112 clamped betweenthe upper stamp 364 b and the lower stamp 364 a of the assembly 322 a.Also, the opening 372 in the upper stamp 364 b can be seen in FIG. 6.

In the following, further details of embodiments of the third aspect ofthe invention will be described. In accordance with the third aspect ofthe invention an advanced passivation station is provided andembodiments thereof will now be described with reference to FIG. 7.

FIG. 7 is an enlarged view of the passivation station shown in FIG. 3.FIG. 7 shows the upper and lower nozzle 328 a and 328 b for dispensing apassivation material onto the edge of the stack 366. FIG. 7 shows partlythe assembly station 322 b of FIG. 3. As can be seen, the stamps 364 aand 364 b clamp the stack 366 there between. The stamps 364 a and 364 bare arranged such that the stack 366 is at an elevated position abovethe receiving area 360 of the assembly station, wherein the distance isselected such that the stack 366 is arranged between the nozzles 328 aand 328 b. The stack 366 is rotated and during the rotation apassivating material is applied via the nozzles 328 a and 328 b fromabove and below so that the edge 116 of the central silicon disc 100 iscovered by the passivating material.

FIG. 8 is a photographic representation of the stack 366 still heldbetween the stamps 364 a and 364 b, however the passivation has alreadybeen completed. The passivation 122 covers the exposed portions of thesilicon disc while leaving the edges of the upper 106 and lower 112copper discs uncovered. In FIG. 8 a situation is shown where theassembly station 322 b of FIG. 7 after completing the passivationprocess has been moved back to the position shown at reference sign 322a of FIG. 3 and the gripper arm 352 b of the robot 310 already engagesthe stack 366. As can be seen, the lower bars 354 a and 354 b are placedaround the lower stamp 364 a whereas the upper bar 356 extends throughthe opening 372 in the upper stamp 364 b. As soon as the gripper 352 bstarts applying a clamping force the clamping force applied by thestamps 364 a, 364 b is reduced and finally the stack 366 is releasedfrom the stamps so that it can be transported by means of the robot 310from the assembly station towards the heating station 306.

This arrangement allows for the provision of an active clamp force ofthe four discs and the silicon chip at any time after assembly until theprocess step of preheating, thereby ensuring the correct centering ofthe five discs.

In the following, further details of embodiments of the fourth aspect ofthe invention will be described. In accordance with the fourth aspect ofthe invention a dynamic process control system controlling the assemblyand passivation of the power disc devices is provided and embodimentsthereof will now be described with reference to FIG. 9 and FIG. 10.

In accordance with embodiments of the invention, during assembly of thestack at the assembly station 322 a and during the passivation processthe stack 366 is monitored to ensure that the stack is correctly formedand further to ensure that a correct amount of passivation material isapplied, which is within the prescribed parameters.

FIG. 9 shows schematically the systems associated with the assemblystations and the passivation station for monitoring the assembly andpassivation process. FIG. 9A shows schematically a camera 800 positionedat the assembly block 322 to monitor the edge 368 of the pellet or stack366 held between the upper and lower stamps 364 b and 364 a of theclamping device of the assembly station. The camera 800 is positioned insuch a way that it “looks” into a direction tangential with respect tothe edge 368 of the stack 366. The observed part of the stack isilluminated by a backlight 802 as it is schematically shown in FIG. 9A.A similar arrangement is provided at the passivation station, as isshown in FIG. 9B. Again, a camera 804 is provided to look in a directiontangential to the edge 368′ of the passivated or almost passivated stack366. Again, the spot detected by the camera 804 is illuminated by alight source providing backlight 806. The camera 800 shown in FIG. 9Amonitors the edge 368 of the assembled stack 366, and the direction fromwhich the respective pictures are taken is indicated in further detailin FIG. 10A. Upon inspection, the assembled stack is rotated and inaccordance with embodiments 24 pictures are taken during one rotation.On the basis of the pictures taken the distance X1 (see FIG. 10( b))between the outer edge 116 of the silicon disc 100 and the edges 118 ofthe remaining discs 104 to 112 can be obtained. In case the value X1deviates from a preset range corrective action may be required, forexample, by an operator of the device. For example, determining that thevalue X1 is for 24 pictures within a predefined range yields a result ofthe test indicating that the discs are correctly centered.

After or during the passivation process, again 24 pictures of therotating, now passivated stack comprising the passivation layer 122 asshown in FIG. 10B are taken and the distance between the outer edge 116′now defined by the outer edge of the passivation layer 122 and the edges118 of the remaining discs is determined. The thickness of thepassivation layer 122 can also be determined. Again, in case the valuesare outside a preset range a warning may be issued.

Further, on the basis of the two measurements the thickness d of thepassivation layer in the radial direction, i.e., the distance betweenthe original edge 116 of the silicon disc 100 and the “new” edge 116′due to the additional passivation layer is determined to make sure thatthe value d is within a preset range. Dependent on the results of themeasurement of the value d corrective action regarding the amount ofmaterial 122 or the position of the respective nozzles may be taken.

For both monitoring processes, in case the results of the monitoringprocess indicate that the parameters derived are outside thespecification, the stack 366 is considered defective and may berejected.

In the following, further details of embodiments of the fifth aspect ofthe invention will be described. In accordance with the fifth aspect ofthe invention an advanced preheating station is provided and embodimentsthereof will now be described with reference to FIG. 11 and FIG. 12.

FIG. 11 shows further details of the heating station, wherein FIG. 11Ashows the heating station 306 comprising the plurality of heatingdevices 336 a to 336 j. The heating devices are of identical structureand FIG. 11B shows one heating device 336 a in its open state and FIG.11C shows the heating device 336 a in its closed state. The heatingdevice comprises two heating brackets 900 a and 900 b that can be movedwith respect to each other so as to open and close the device as shownin FIGS. 11B and 11C. In the example shown in FIG. 11 the lower bracket900 a is vertically moveable with regard to the upper bracket 900 b. Forplacing a passivated stack into a heating device it is opened in a wayas shown in FIG. 11B, and by means of the gripper the stack is placedbetween the two brackets 900 a and 900 b. The lower bracket 900 a isprovided with two recesses 902 a and 902 b for receiving the respectivelower bars of the gripper 352 b, and the upper bracket 900 b is providedwith a recess 900 for receiving the upper bar of the gripper 352 b. Thisallows for placing the stack inside the heating device without releasingthe clamp force until the two brackets 900 a, 900 b are closed and applythe necessary clamping force. By means of the recesses the gripper canbe opened and removed from the closed heating device 336 a shown in FIG.11C. This ensures that, as mentioned above, a continuous clamp force isapplied after assembly of the stack until the preheating is completed.After preheating the stack has a sufficient stability and can be easilyhandled without jeopardizing the centralized arrangement of therespective discs with respect to each other.

In accordance with embodiments the respective brackets 900 a, 900 b ofthe heating device shown in FIG. 11 are heated for applying the desiredheat to the stack provided there between. The heating devices inaccordance with embodiments of the invention are advantageous as whencompared to a conventional oven a fast ramp-up of the temperature and anaccurate and stable temperature is achieved while hardware costs arereduced and also maintenance costs can be reduced. Also, the respectiveelements 336 a to 336 j can be selectively activated so that dependenton the throughput of the system a desired number of heating devices isactivated thereby avoiding unnecessary heating of devices not needed.FIG. 12 shows a photographic representation of an open heating deviceafter preheating the stack 366. FIG. 12 shows the lower bracket 900 aand the upper bracket 900 b as well as the respective recesses 902 a and902 b in the lower bracket 900 a for receiving the lower bars of thegripper 352 b. The stack 366 is now preheated and comprises a sufficientstability to be easily handled for a further processing and testingwithout decentralizing the layered structure.

In accordance with further embodiments single device traceability isprovided by identifying the output trays as well as the reject trays bytransponders. During a lot start the output tray will be automaticallyscanned and correlated with the recipe setting of the equipment. Acluster tool controller (CTC) (see controller 212 in FIG. 2) assures thesingle device traceability of any package output in reference to thetest process result.

Embodiments of the invention described above with respect to the backend cluster provide a fully automated assembly technology that isvisualized by a video and vision system. Two robot systems incombination with the synchronized assembly mechanism are used toassemble five discs with the accuracy of, e.g., 10 micron. Theintegrated dynamic process control system controls the assembly processduring real time production and provides imitated feed pack ofmeasurements within the resolution of, e.g., 2 micron.

Embodiments of the invention were described above with regard to a powerdisc device comprising a silicon layer sandwiched between a plurality ofmetal layers, more specifically sandwiched between two layers of metallayers formed of copper and molybdenum. Naturally, the inventiveapproach is not limited to such devices, rather it can be applied to anydevice in which a semiconductor device needs to be stacked with at leastone additional non-semiconductor device and passivated, wherein thesemiconductor device requires a semiconductor treatment before themechanical assembly step.

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method, where a block or device corresponds to amethod step or a feature of a method step. Analogously, aspectsdescribed in the context of a method step also represent a descriptionof a corresponding block or item or feature of a correspondingapparatus.

The above described embodiments are merely illustrative for theprinciples of the present invention. It is understood that modificationsand variations of the arrangements and the details described herein willbe apparent to others skilled in the art. It is the intent, therefore,to be limited only by the scope of the impending patent claims and notby the specific details presented by way of description and explanationof the embodiments herein.

1. A system for producing devices that include a semiconductor part anda non-semiconductor part, the system comprising: a front end configuredto receive a semiconductor part and to process the semiconductor part; aback end configured to receive the processed semiconductor part and toassemble the processed semiconductor part and a non-semiconductor partinto a device; and a transfer device configured to automatically handlethe semiconductor part in the front end and to automatically transferthe processed semiconductor part to the back end, wherein the back endcomprises: an assembly station configured to assemble the parts into astack; a passivation station; and a heating station.
 2. The system ofclaim 1, wherein the transfer device comprises a robot having an armprovided with a gripper configured to grip the semiconductor part. 3.The system of claim 1, wherein the front end comprises an etchingstation and a test station, and wherein the transfer device isconfigured to insert/remove a semiconductor part into/from a respectivestation.
 4. The system of claim 3, wherein the back end comprises anintermediate tray configured to receive a processed semiconductor part,and wherein the transfer device is configured to transfer asemiconductor part from an input of the front end to the etchingstation, from the etching station to the test station, and from the teststation to the intermediate tray of the back end in case the processedsemiconductor part passed the test, to a reject bin in case theprocessed semiconductor part did not pass the test, or back into theetch station in case the test indicates that additional etching isrequired.
 5. The system of claim 1, wherein the assembly station isconfigured to receive one or more non-semiconductor parts and theprocessed semiconductor part for forming the stack, and wherein theassembly station comprises: a centering device configured to center thenon-semiconductor parts of the stack; and a clamping device configuredto apply a clamp force to a top and a bottom of the stack.
 6. The systemof claim 5, wherein the centering device comprises a plurality ofcentering elements arranged at different positions around a receivingarea of the assembly station, wherein each of the centering elements ismoveable in a vertical direction and in a radial direction; and whereinthe assembly station is configured to form the stack by: receiving atleast one first non-semiconductor part; moving the centering elementsradially inward for centering the first non-semiconductor part;receiving the processed semiconductor part on the firstnon-semiconductor part, wherein a diameter of the processedsemiconductor part is larger than the diameter of the firstnon-semiconductor part; receiving at least one second non-semiconductorpart on the processed semiconductor part; moving the centering elementsradially outward and vertically so as to allow the centering elements topass the processed semiconductor part, and radially inward after havingpassed the processed semiconductor part for centering the secondnon-semiconductor part; and activating the clamping device for applyinga clamp force to the stack.
 7. The system of claim 6, wherein theclamping device is configured to raise the stack to a position elevatedwith respect to the receiving area, while maintaining the clamp force.8. The system of claim 6, wherein the back end comprises a transferdevice and a position detecting device configured to detect a positionof a processed semiconductor part held by the transfer device withrespect to the transfer device, and wherein the transfer device isconfigured to be controlled on a basis of the detected position forplacing the processed semiconductor part centered on the firstnon-semiconductor part.
 9. The system of claim 8, wherein the clampingdevice comprises a lower stamp and an upper stamp that are verticallymoveable for an engagement with a stack and for application of the clampforce, wherein the transfer device comprises a gripper configured tohold a processed semiconductor part for placement in the assemblystation and to hold the assembled stack while applying the clamp force,and wherein of the clamping device and of the transfer device areconfigured such that the clamping device releases the clamp force onlyonce the gripper of the transfer device engaged the stack and appliedthe clamp force to the stack so as to ensure a continuous application ofthe clamp force to the stack.
 10. The system of claim 6, furthercomprising a first monitoring device configured to optically monitor anedge of the assembled stack to determine along a periphery at predefinedintervals a first distance between an outer edge of the processedsemiconductor part and an outer edge of the first and secondnon-semiconductor parts.
 11. The system of claim 1, wherein thepassivation station comprises a nozzle device configured to apply apassivation material to an edge of the stack such that the edge of theprocessed semiconductor part is covered with the passivation material.12. The system of claim 11, wherein the nozzle device comprises a topnozzle and a bottom nozzle for applying the passivation material. 13.The system of claim 11, further comprising a first monitoring deviceconfigured to optically monitor an edge of the assembled stack todetermine along the periphery at predefined intervals a first distancebetween an outer edge of the processed semiconductor part and an outeredge of the first and second non-semiconductor parts, and a secondmonitoring device configured to optically monitor an edge of the stackto which the passivation material was applied to determine at aplurality of predefined intervals a second distance between an outeredge of the passivation material on the processed semiconductor part andan outer edge of first and second non-semiconductors, wherein the systemis configured to determine on a basis of first and second distances athickness of the passivation material in a radial direction provided onthe edge of the processed semiconductor part.
 14. The system of claim13, wherein the nozzle device is arranged radially moveable with regardto a stack edge, and wherein the nozzle device is configured to becontrolled with respect to its position and/or the amount of passivationmaterial dispensed on the basis of the determined thickness.
 15. Thesystem of claim 1, wherein the heating station comprises a pair ofheating brackets configured to be moveable with respect to each otherand to receive the stack there between.
 16. The system of claim 15,wherein the heating brackets are configured such that a gripper of atransfer device placing the stack there between releases the stack onlyonce the heating brackets were closed and apply a clamp force so as toensure a continuous application of the clamp force to the stack.
 17. Thesystem of claim 15, comprising a plurality of heating stationsconfigured to be selectively activated dependent on a number of stacksproduced.
 18. The system of claim 1, wherein the device to be assembledcomprises a power disc device including a semiconductor chip sandwichedbetween a plurality of metal discs, wherein the semiconductor chip has alarger diameter than the metal discs and an etched edge.
 19. The systemof claim 18, wherein the semiconductor chip is placed between a firstpair of metal discs and a second pair of metal discs, the first andsecond pairs each including a copper disc and a molybdenum disc.
 20. Asystem for producing a power disc device comprising a semiconductor discsandwiched between a plurality of metal discs, the system comprising: afront end semiconductor processing station comprising a plurality ofetching stations and a test station, the etching stations beingconfigured to etch an edge of a semiconductor disc, and the test stationbeing configured to test the etched semiconductor disc; a back enddevice assembly station comprising: an assembly station configured toassemble the etched semiconductor disc and a plurality of metal discsinto a stack, wherein the etched semiconductor disc has a largerdiameter than the metal discs, a passivation station configured to applya passivation material to the edge of the stack to cover exposed area ofthe etched semiconductor disc, and a heating station configured toreceive the stack and to heat the stack; and a robot comprising an armprovided with a gripper and configured to handle the semiconductor discin the front end semiconductor processing station and to transfer theetched semiconductor disc from the front end semiconductor processingstation to the back end device assembly station.
 21. The system of claim20, wherein the assembly station comprises a centering device configuredto center the metal discs, and a clamping device configured to apply aclamp force to the stack, wherein the assembly station is arrangedmovably between a first position for receiving the semiconductor andmetal discs and a second position at which the stack is arranged betweentwo nozzles of the passivation station for applying the passivationmaterial to the stack, and wherein the system further comprises amonitoring device configured to optically monitor the stack afterassembly and after passivation to determine a a distance between anouter edge of the semiconductor and metal discs, and a thickness of thepassivation material in a radial direction.
 22. The system of claim 21,wherein the back end device assembly station comprises a robot fortransferring the passivated stack to the heating station, wherein theclamping device is configured to release the passivated stack only oncethe clamp force is applied by a gripper of the robot, and wherein thegripper of the robot is configured to release the passivated stack inthe heating station only once the heating station applied the clampforce to the stack.
 23. A system for producing devices including asemiconductor part and a non-semiconductor part, the system comprising:a front end configured to receive a semiconductor part and to processthe semiconductor part; a back end configured to receive the processedsemiconductor part and the non-semiconductor part and to assemble theparts into a device; and means for automatically handling thesemiconductor part in the front end and for automatically transferringthe processed semiconductor part to the back end, wherein the back endcomprises: an assembly station configured to assemble the parts into astack; a passivation station; and a heating station.
 24. A method forproducing devices including a semiconductor part and a non-semiconductorpart, the method comprising: receiving and processing a semiconductorpart at a front end processing station; automatically handling thesemiconductor part in the front end processing station and automaticallytransferring the processed semiconductor part to a back end processingstation by a transfer device; and receiving and assembling the processedsemiconductor part and a non-semiconductor part at a back end processingstation, wherein the back end comprise: an assembly station configuredto assemble the parts into a stack; a passivation station; and a heatingstation.